Hand tools today are typically powered by rechargeable batteries. Most common among these batteries are the nickel cadmium batteries which are low voltage and high energy power sources attractive for use in such devices. However, such batteries are quite expensive and, accordingly, it is most desirable that the number of such batteries used in any particular device be kept at a minimum.
In certain applications such as electric staple guns and the like, there is a need for the provision of high levels of power for short durations of time. In the example of a staple gun, when the operative solenoid is activated by a MOSFET, there is a substantial need for a high level of actuating power through the solenoid and MOSFET for a very short duration of time. While a simple series interconnection of a plurality of NiCad batteries could provide the requisite power level, in the example just given as many as seven NiCad batteries could be required to provide the requisite power surge on demand. The cost of the NiCad batteries would, in such an instance, be prohibitive.
While it is a rather simple proposition to increase voltage from an AC power source, it is a more difficult proposition in systems employing DC power sources. Specifically, while it is quite simple to employ transformers or the like to step-up a voltage level on an AC basis, it is a more difficult proposition to obtain such an increase when the system employs a DC power source. Indeed, when the power source is necessarily DC, as in hand tools, the cost of converting the DC source to an AC signal for employment of transformers and the like substantially depletes the savings enjoyed by the reduction in the number of NiCad batteries required for simple series interconnection.
It is further desired that the actuation of the hand tool be undertaken by a positive overt command, not given to misfiring, double firing, or the like. In hand tools such as staple guns, rivet guns, nailers, and the like, such safety features are most desirable.